It is known in the art to use various types of miniature integrated or hybrid systems using various mechanisms or components to deflect a beam of light.
A first system comprises one or more rotating or oscillating mirrors. The reflection of a light beam on a rotating mirror is used to achieve high scanning speeds. This type of system is often very sensitive to acceleration, which is a drawback, particular in on-board laser telemetry applications.
Some deflection devices use networks of microlenses. Examples of this type of system were described by E. A. Watson in "Analysis of beam steering with decentered microlens array" in Optical Engineering, November 1993, vol. 32, No. 11, pages 2665-2670 and in T. D. Milster et al. in SPIE, vol. 1625, "Design, Modeling and Control of Laser Beam Optics", 1992, pages 78-83. These systems use the deviation caused by a disalignment of the optical axis of a moving system of microlenses or network of microlenses. This type of device cannot be used to produce a highly-integrated microdeflector.
Most light microdeflector systems use piezoelectric components to control the movement of the moving parts. This has the drawback that such components are often bulky and are thus limited to low frequencies. The piezoelectric components also require very high control voltages (in the region of 1,000 volts) which make it difficult to attain high frequencies without excessively high power consumption. Another drawback of high voltages lies in the cost of power supplies that are difficult to miniaturize.
A different system was described in French patent application FR-A-95 05652. This document describes a microscanning device that uses microlenses and electrostatic struts integrated on a substrate. The axis of the microlens is perpendicular to the substrate on which it is fabricated. The device presented in said document is advantageous in situations where microscanning of a beam in two directions is required. However, where microscanning of a beam in a single direction is required, a more simply-made device could be found, giving a cheaper system. Moreover, the technique described in FR-A-95 05652 does not allow for making all types of lenses, particularly lenses with a very short focal length used to give wider scanning angles. Nor does it allow for lower control voltages for equivalent scanning angles. Finally, the device described in application FR-A-95 05652 enables lenses to be stacked along an axis but does this by crossing two microstruts at 90.degree. on two levels. It is therefore sometimes necessary to displace an entire series of microlenses all together.
The document U.S. Pat. No. 5,097,354 describes a hybrid device comprising a point light-source, a lens and a mechanism for displacing the lens or the light-source. This device requires assembling the mechanical component on a support of the light-source and the lens on the mechanical component. The optical system must be mounted very accurately on the mechanical component. This type of device in which a lens is mounted on a mechanical structure is described as "hybrid" and requires alignment and assembly operations that are incompatible with mass production.